Erosion includes all such processes by which the mobile agencies acquire and remove rock materials. Commonly, transportation is considered as an integral part of erosion. Erosion takes place in many ways.

The mechanism by which loose materials are acquired by the river and swept away is the hydraulic action. That is the sweeping away of loose materials. Corresponding mechanism by the wind is deflation and when performed by the glacier it is termed as scouring. Two other mechanisms by which the glaciers acquire the materials are plucking and sapping. Plucking means the acquisition of parts of the bedrock by a glacier when frosting and heaving disintegrate the bed rock. Sapping, on the other hand, is undermining of the bed rock.

Processes by which the agents erode the earth materials while in transit, corrasion (or abrasion) and corrosion. Corrasion is the mechanical abrasion the rocks on the river bed and the sides. The running water carries boulders, r fragments, which dash against the bed rock and the sides resulting in the erosi of the river bed and the sides. Corrosion means the chemical erosion by wat especially, when it is charged with alkalies, carbonates, acids etc. Similarly Corrosion is affected by the wind action and glaciers. (Glaciers also erode t earth materials by gouging, i.e. the local basining of the softer bed rock, which! also a process of corrasion).

During transit, the rock fragments are eroded by wear and tear through mutu rubbing, grinding, knocking, scrapping etc. This mechanism is known as attrition performed by the river, the glaciers and the wind.